Brown's syndrome with ocular albinism: Case report of a rare presentation and literature review.

We report a rare case of Brown's syndrome associated with ocular albinism in a 10-year-old boy. This report highlights the importance of further analysis of cases of Brown's syndrome and throws some light on the etiology and association of this rare condition.

Introduction

Brown's syndrome is characterized by the inability of the eye to elevate in adducted position, both actively and passively on forced duction test. Brown's syndrome occurs, usually, as an isolated anomaly although other associated anomalies have been published in the past, which includes Duanes syndrome, crocodile tears, congenital ptosis, Marcus Gunn synkinetic movements, coloboma of the choroid and congenital cardiac anomalies.[12345]

We report a case of Brown's syndrome associated with ocular albinism in a 10-year-old boy. This presentation is a rare association and this to our knowledge is the first such reported case in the literature.

Case Report

A 10-year-old boy presented with a history of diminution of vision left face turn, nystagmus and photophobia of both eyes for the last 7 years. There were no similar complaints in the family members and no history of any trauma or any systemic disease. He had a visual acuity of 20/100 in right eye (RE) and 20/80 in left eye (LE) (Snellen visual acuity chart) and was not improving with correction. His near vision was N6 in both eyes (Times new roman chart). Cycloplegic refraction showed a refractive error of + 1.0 Dioptre Sphere (DS) −1.5 Dioptre cylinder (DC) at 180° in the RE and + 0.5 DS − 1.0 DC at 160° in the LE.

The child adopted a left face turn for both distance and near. Cover test for distance and near, showing a left hypertropia in the forced primary position. A Prism Bar Cover test showed 20 prism diopters (PD) of left hypertropia for distance and 15 PD of left hypertropia for near. He was orthophoric in the preferred head posture. Ocular movements in RE showed a limited elevation in midline and on adduction. Elevation was normal in abduction [Figure 1]. Worth Four Dot Test revealed the fusion for near and distance with the preferred head posture. Stereoacuity with Randot showed a stereopsis of 600 s of arc. A horizontal jerk nystagmus with null point in the right gaze was seen. On slit lamp examination, iris hypopigmentation with transillumination defects was seen with normal pupillary reaction. Indirect ophthalmoscopic examination showed an albinotic fundus with foveal hypoplasia [Figures 2a and b, 3a and b]. The foveal hypoplasia was confirmed on optical coherence tomography (Cirrus; Carl Zeiss Meditec, Dublin, CA) [Figure 4]. However a 3-lead visual evoked potentials was not performed.

Figure 1

Nine gaze photograph showing limited elevation in midline and adduction in right eye

Figure 2

Foveal hypoplasia seen on color fundus photography OU (a and b)

Figure 3

Foveal hypoplasia seen on red free fundus photography OU (a and b)

Figure 4

Optical coherence tomography picture demonstrating the foveal hypoplasia with absence of foveal pit

Discussion

Brown's syndrome is caused by an abnormality in the superior oblique tendon trochlea complex. The syndrome may present in a congenital, acquired, constant, or intermittent form.[6] The syndrome has constant features like absence of elevation in adduction and normal elevation in abduction. Forced ductions show severe mechanical restriction on attempts to elevate the adducted eye and no limitation of elevation in abduction. Variable features include mild limitation of elevation from the primary position, down shoot in adduction, widening of lid fissure, hypotropia in the primary position, compensatory head posture.[1] Patients with Brown's syndrome usually have excellent binocular fusion, as they adopt a compensatory chin elevation or a face turn away from the Brown's eye to maintain fusion.

Albinism, on the other hand, refers to disorders of reduced pigmentation compared with others of the same ethnic and racial backgrounds with characteristic ocular involvement.

If there is little or no detectable loss of pigmentation of the skin and hair, the disorder is usually referred to as ocular albinism, as in our case.

The association of hypopigmentation of the skin and hair is referred to as oculocutaneous albinism.[7]

Nystagmus is usually present in persons with albinism. With age, the nystagmus eventually matures into a pendular form followed later by a typical jerk nystagmus. Anomalous head positions may be observed.

In our case, though the child had good fusion, he had a moderate reduction in vision and stereopsis which could possibly be due to either nystagmus or due to the foveal hypoplasia associated with albinism and may not have been due to Brown's syndrome. Brown in his series of 126 patients had reported that amblyopia was insignificant in his series.[8] It is seen that macular hypoplasia is the most common vision limiting abnormality in patients with albinism.[7] Optical coherence tomography may be useful in documenting the presence of macular hypoplasia and will demonstrate an absence of the foveal pit and loss of the usual thinning of the retina in this area, as in our case.

The head posture maintained by the child could have been either for a null point or secondary to the Brown's syndrome and this differentiation may be a prerequisite to decide on the management.

Brown's syndrome occurs, usually, as an isolated anomaly. The other anomalies associated includes duanes syndrome, crocodile tears, congenital ptosis, Marcus Gunn synkinetic movements, coloboma of the choroid, congenital cardiac anomalies.[12345] Though rare, a knowledge of these associations is important to find if any genetic association exists and thus throw some light on the etiology of this syndrome. Both albinism and Brown's syndrome have been found to have genetic association.[78910] Whether these could have a common pathogenesis is unknown. The infrequent occurrence of associated anomalies raises the distinct possibility that these are coincidental findings rather than true associations, but a genetic analysis may be required to rule out a true association. To our knowledge, this is the first case report in which Brown's syndrome is associated with ocular albinism.